meta: Split GenerateMipmap() into its own file.

Putting the implementation of each GL function in its own file makes it
much easier not to get lost.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Matt Turner <[email protected]>
Reviewed-by: Anuj Phogat <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

3 files changed, 376 insertions, 337 deletions

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 2ac7867e63d..030e1116e9e 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -89,7 +89,6 @@ choose_blit_shader(GLenum target, struct blit_shader_table *table);
 
 static void cleanup_temp_texture(struct temp_texture *tex);
 static void meta_glsl_clear_cleanup(struct clear_state *clear);
-static void meta_glsl_generate_mipmap_cleanup(struct gen_mipmap_state *mipmap);
 static void meta_decompress_cleanup(struct decompress_state *decompress);
 static void meta_drawpix_cleanup(struct drawpix_state *drawpix);
 
@@ -361,7 +360,7 @@ _mesa_meta_free(struct gl_context *ctx)
    _mesa_make_current(ctx, NULL, NULL);
    _mesa_meta_glsl_blit_cleanup(&ctx->Meta->Blit);
    meta_glsl_clear_cleanup(&ctx->Meta->Clear);
-   meta_glsl_generate_mipmap_cleanup(&ctx->Meta->Mipmap);
+   _mesa_meta_glsl_generate_mipmap_cleanup(&ctx->Meta->Mipmap);
    cleanup_temp_texture(&ctx->Meta->TempTex);
    meta_decompress_cleanup(&ctx->Meta->Decompress);
    meta_drawpix_cleanup(&ctx->Meta->DrawPix);
@@ -2360,102 +2359,6 @@ _mesa_meta_Bitmap(struct gl_context *ctx,
    _mesa_meta_end(ctx);
 }
 
-
-/**
- * Check if the call to _mesa_meta_GenerateMipmap() will require a
- * software fallback.  The fallback path will require that the texture
- * images are mapped.
- * \return GL_TRUE if a fallback is needed, GL_FALSE otherwise
- */
-GLboolean
-_mesa_meta_check_generate_mipmap_fallback(struct gl_context *ctx, GLenum target,
-                                          struct gl_texture_object *texObj)
-{
-   const GLuint fboSave = ctx->DrawBuffer->Name;
-   struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
-   struct gl_texture_image *baseImage;
-   GLuint srcLevel;
-   GLenum status;
-
-   /* check for fallbacks */
-   if (target == GL_TEXTURE_3D ||
-       target == GL_TEXTURE_1D_ARRAY ||
-       target == GL_TEXTURE_2D_ARRAY) {
-      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
-                       "glGenerateMipmap() to %s target\n",
-                       _mesa_lookup_enum_by_nr(target));
-      return GL_TRUE;
-   }
-
-   srcLevel = texObj->BaseLevel;
-   baseImage = _mesa_select_tex_image(ctx, texObj, target, srcLevel);
-   if (!baseImage) {
-      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
-                       "glGenerateMipmap() couldn't find base teximage\n");
-      return GL_TRUE;
-   }
-
-   if (_mesa_is_format_compressed(baseImage->TexFormat)) {
-      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
-                       "glGenerateMipmap() with %s format\n",
-                       _mesa_get_format_name(baseImage->TexFormat));
-      return GL_TRUE;
-   }
-
-   if (_mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB &&
-       !ctx->Extensions.EXT_texture_sRGB_decode) {
-      /* The texture format is sRGB but we can't turn off sRGB->linear
-       * texture sample conversion.  So we won't be able to generate the
-       * right colors when rendering.  Need to use a fallback.
-       */
-      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
-                       "glGenerateMipmap() of sRGB texture without "
-                       "sRGB decode\n");
-      return GL_TRUE;
-   }
-
-   /*
-    * Test that we can actually render in the texture's format.
-    */
-   if (!mipmap->FBO)
-      _mesa_GenFramebuffers(1, &mipmap->FBO);
-   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, mipmap->FBO);
-
-   if (target == GL_TEXTURE_1D) {
-      _mesa_FramebufferTexture1D(GL_FRAMEBUFFER_EXT,
-                                    GL_COLOR_ATTACHMENT0_EXT,
-                                    target, texObj->Name, srcLevel);
-   }
-#if 0
-   /* other work is needed to enable 3D mipmap generation */
-   else if (target == GL_TEXTURE_3D) {
-      GLint zoffset = 0;
-      _mesa_FramebufferTexture3D(GL_FRAMEBUFFER_EXT,
-                                    GL_COLOR_ATTACHMENT0_EXT,
-                                    target, texObj->Name, srcLevel, zoffset);
-   }
-#endif
-   else {
-      /* 2D / cube */
-      _mesa_FramebufferTexture2D(GL_FRAMEBUFFER_EXT,
-                                    GL_COLOR_ATTACHMENT0_EXT,
-                                    target, texObj->Name, srcLevel);
-   }
-
-   status = _mesa_CheckFramebufferStatus(GL_FRAMEBUFFER_EXT);
-
-   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, fboSave);
-
-   if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
-      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
-                       "glGenerateMipmap() got incomplete FBO\n");
-      return GL_TRUE;
-   }
-
-   return GL_FALSE;
-}
-
-
 /**
  * Compute the texture coordinates for the four vertices of a quad for
  * drawing a 2D texture image or slice of a cube/3D texture.
@@ -2698,245 +2601,6 @@ _mesa_meta_blit_shader_table_cleanup(struct blit_shader_table *table)
    table->sampler_cubemap_array.shader_prog = 0;
 }
 
-static void
-meta_glsl_generate_mipmap_cleanup(struct gen_mipmap_state *mipmap)
-{
-   if (mipmap->VAO == 0)
-      return;
-   _mesa_DeleteVertexArrays(1, &mipmap->VAO);
-   mipmap->VAO = 0;
-   _mesa_DeleteBuffers(1, &mipmap->VBO);
-   mipmap->VBO = 0;
-
-   _mesa_meta_blit_shader_table_cleanup(&mipmap->shaders);
-}
-
-
-/**
- * Called via ctx->Driver.GenerateMipmap()
- * Note: We don't yet support 3D textures, 1D/2D array textures or texture
- * borders.
- */
-void
-_mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
-                          struct gl_texture_object *texObj)
-{
-   struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
-   struct vertex verts[4];
-   const GLuint baseLevel = texObj->BaseLevel;
-   const GLuint maxLevel = texObj->MaxLevel;
-   const GLint maxLevelSave = texObj->MaxLevel;
-   const GLboolean genMipmapSave = texObj->GenerateMipmap;
-   const GLuint fboSave = ctx->DrawBuffer->Name;
-   const GLuint currentTexUnitSave = ctx->Texture.CurrentUnit;
-   const GLboolean use_glsl_version = ctx->Extensions.ARB_vertex_shader &&
-                                      ctx->Extensions.ARB_fragment_shader;
-   GLenum faceTarget;
-   GLuint dstLevel;
-   const GLint slice = 0;
-   GLuint samplerSave;
-
-   if (_mesa_meta_check_generate_mipmap_fallback(ctx, target, texObj)) {
-      _mesa_generate_mipmap(ctx, target, texObj);
-      return;
-   }
-
-   if (target >= GL_TEXTURE_CUBE_MAP_POSITIVE_X &&
-       target <= GL_TEXTURE_CUBE_MAP_NEGATIVE_Z) {
-      faceTarget = target;
-      target = GL_TEXTURE_CUBE_MAP;
-   }
-   else {
-      faceTarget = target;
-   }
-
-   _mesa_meta_begin(ctx, MESA_META_ALL);
-
-   /* Choose between glsl version and fixed function version of
-    * GenerateMipmap function.
-    */
-   if (use_glsl_version) {
-      _mesa_meta_setup_vertex_objects(&mipmap->VAO, &mipmap->VBO, true,
-                                      2, 3, 0);
-      _mesa_meta_setup_blit_shader(ctx, target, &mipmap->shaders);
-   }
-   else {
-      _mesa_meta_setup_ff_tnl_for_blit(&mipmap->VAO, &mipmap->VBO, 3);
-      _mesa_set_enable(ctx, target, GL_TRUE);
-   }
-
-   samplerSave = ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler ?
-      ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler->Name : 0;
-
-   if (currentTexUnitSave != 0)
-      _mesa_BindTexture(target, texObj->Name);
-
-   if (!mipmap->FBO) {
-      _mesa_GenFramebuffers(1, &mipmap->FBO);
-   }
-
-   if (!mipmap->Sampler) {
-      _mesa_GenSamplers(1, &mipmap->Sampler);
-      _mesa_BindSampler(ctx->Texture.CurrentUnit, mipmap->Sampler);
-
-      _mesa_SamplerParameteri(mipmap->Sampler,
-                              GL_TEXTURE_MIN_FILTER,
-                              GL_LINEAR_MIPMAP_LINEAR);
-      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
-
-      /* We don't want to encode or decode sRGB values; treat them as linear.
-       * This is not technically correct for GLES3 but we don't get any API
-       * error at the moment.
-       */
-      if (ctx->Extensions.EXT_texture_sRGB_decode) {
-         _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_SRGB_DECODE_EXT,
-               GL_SKIP_DECODE_EXT);
-      }
-
-   } else {
-      _mesa_BindSampler(ctx->Texture.CurrentUnit, mipmap->Sampler);
-   }
-
-   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, mipmap->FBO);
-
-   _mesa_TexParameteri(target, GL_GENERATE_MIPMAP, GL_FALSE);
-
-   /* Silence valgrind warnings about reading uninitialized stack. */
-   memset(verts, 0, sizeof(verts));
-
-   /* Setup texture coordinates */
-   _mesa_meta_setup_texture_coords(faceTarget,
-                                   slice,
-                                   0, 0, 1, /* width, height never used here */
-                                   verts[0].tex,
-                                   verts[1].tex,
-                                   verts[2].tex,
-                                   verts[3].tex);
-
-   /* setup vertex positions */
-   verts[0].x = -1.0F;
-   verts[0].y = -1.0F;
-   verts[1].x =  1.0F;
-   verts[1].y = -1.0F;
-   verts[2].x =  1.0F;
-   verts[2].y =  1.0F;
-   verts[3].x = -1.0F;
-   verts[3].y =  1.0F;
-
-   /* upload vertex data */
-   _mesa_BufferData(GL_ARRAY_BUFFER_ARB, sizeof(verts),
-                       verts, GL_DYNAMIC_DRAW_ARB);
-
-   /* texture is already locked, unlock now */
-   _mesa_unlock_texture(ctx, texObj);
-
-   for (dstLevel = baseLevel + 1; dstLevel <= maxLevel; dstLevel++) {
-      const struct gl_texture_image *srcImage;
-      const GLuint srcLevel = dstLevel - 1;
-      GLsizei srcWidth, srcHeight, srcDepth;
-      GLsizei dstWidth, dstHeight, dstDepth;
-      GLenum status;
-
-      srcImage = _mesa_select_tex_image(ctx, texObj, faceTarget, srcLevel);
-      assert(srcImage->Border == 0);
-
-      /* src size */
-      srcWidth = srcImage->Width;
-      srcHeight = srcImage->Height;
-      srcDepth = srcImage->Depth;
-
-      /* new dst size */
-      dstWidth = MAX2(1, srcWidth / 2);
-      dstHeight = MAX2(1, srcHeight / 2);
-      dstDepth = MAX2(1, srcDepth / 2);
-
-      if (dstWidth == srcImage->Width &&
-          dstHeight == srcImage->Height &&
-          dstDepth == srcImage->Depth) {
-         /* all done */
-         break;
-      }
-
-      /* Allocate storage for the destination mipmap image(s) */
-
-      /* Set MaxLevel large enough to hold the new level when we allocate it */
-      _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, dstLevel);
-
-      if (!_mesa_prepare_mipmap_level(ctx, texObj, dstLevel,
-                                      dstWidth, dstHeight, dstDepth,
-                                      srcImage->Border,
-                                      srcImage->InternalFormat,
-                                      srcImage->TexFormat)) {
-         /* All done.  We either ran out of memory or we would go beyond the
-          * last valid level of an immutable texture if we continued.
-          */
-         break;
-      }
-
-      /* limit minification to src level */
-      _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, srcLevel);
-
-      /* Set to draw into the current dstLevel */
-      if (target == GL_TEXTURE_1D) {
-         _mesa_FramebufferTexture1D(GL_FRAMEBUFFER_EXT,
-                                       GL_COLOR_ATTACHMENT0_EXT,
-                                       target,
-                                       texObj->Name,
-                                       dstLevel);
-      }
-      else if (target == GL_TEXTURE_3D) {
-         GLint zoffset = 0; /* XXX unfinished */
-         _mesa_FramebufferTexture3D(GL_FRAMEBUFFER_EXT,
-                                       GL_COLOR_ATTACHMENT0_EXT,
-                                       target,
-                                       texObj->Name,
-                                       dstLevel, zoffset);
-      }
-      else {
-         /* 2D / cube */
-         _mesa_FramebufferTexture2D(GL_FRAMEBUFFER_EXT,
-                                       GL_COLOR_ATTACHMENT0_EXT,
-                                       faceTarget,
-                                       texObj->Name,
-                                       dstLevel);
-      }
-
-      _mesa_DrawBuffer(GL_COLOR_ATTACHMENT0_EXT);
-
-      /* sanity check */
-      status = _mesa_CheckFramebufferStatus(GL_FRAMEBUFFER_EXT);
-      if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
-         _mesa_problem(ctx, "Unexpected incomplete framebuffer in "
-                       "_mesa_meta_GenerateMipmap()");
-         break;
-      }
-
-      assert(dstWidth == ctx->DrawBuffer->Width);
-      assert(dstHeight == ctx->DrawBuffer->Height);
-
-      /* setup viewport */
-      _mesa_set_viewport(ctx, 0, 0, 0, dstWidth, dstHeight);
-
-      _mesa_DrawArrays(GL_TRIANGLE_FAN, 0, 4);
-   }
-
-   _mesa_lock_texture(ctx, texObj); /* relock */
-
-   _mesa_BindSampler(ctx->Texture.CurrentUnit, samplerSave);
-
-   _mesa_meta_end(ctx);
-
-   _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, maxLevelSave);
-   if (genMipmapSave)
-      _mesa_TexParameteri(target, GL_GENERATE_MIPMAP, genMipmapSave);
-
-   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, fboSave);
-}
-
-
 /**
  * Determine the GL data type to use for the temporary image read with
  * ReadPixels() and passed to Tex[Sub]Image().
diff --git a/src/mesa/drivers/common/meta.h b/src/mesa/drivers/common/meta.h
index d2f40f86ac1..16bd427eb99 100644
--- a/src/mesa/drivers/common/meta.h
+++ b/src/mesa/drivers/common/meta.h
@@ -502,4 +502,7 @@ _mesa_meta_glsl_blit_cleanup(struct blit_state *blit);
 void
 _mesa_meta_blit_shader_table_cleanup(struct blit_shader_table *table);
 
+void
+_mesa_meta_glsl_generate_mipmap_cleanup(struct gen_mipmap_state *mipmap);
+
 #endif /* META_H */
diff --git a/src/mesa/drivers/common/meta_generate_mipmap.c b/src/mesa/drivers/common/meta_generate_mipmap.c
new file mode 100644
index 00000000000..f1bc291fc58
--- /dev/null
+++ b/src/mesa/drivers/common/meta_generate_mipmap.c
@@ -0,0 +1,372 @@
+/*
+ * Mesa 3-D graphics library
+ *
+ * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * Meta operations.  Some GL operations can be expressed in terms of
+ * other GL operations.  For example, glBlitFramebuffer() can be done
+ * with texture mapping and glClear() can be done with polygon rendering.
+ *
+ * \author Brian Paul
+ */
+
+#include "main/arrayobj.h"
+#include "main/buffers.h"
+#include "main/enums.h"
+#include "main/enable.h"
+#include "main/fbobject.h"
+#include "main/macros.h"
+#include "main/mipmap.h"
+#include "main/teximage.h"
+#include "main/texobj.h"
+#include "main/texparam.h"
+#include "main/varray.h"
+#include "main/viewport.h"
+#include "drivers/common/meta.h"
+
+/**
+ * Check if the call to _mesa_meta_GenerateMipmap() will require a
+ * software fallback.  The fallback path will require that the texture
+ * images are mapped.
+ * \return GL_TRUE if a fallback is needed, GL_FALSE otherwise
+ */
+GLboolean
+_mesa_meta_check_generate_mipmap_fallback(struct gl_context *ctx, GLenum target,
+                                          struct gl_texture_object *texObj)
+{
+   const GLuint fboSave = ctx->DrawBuffer->Name;
+   struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
+   struct gl_texture_image *baseImage;
+   GLuint srcLevel;
+   GLenum status;
+
+   /* check for fallbacks */
+   if (target == GL_TEXTURE_3D ||
+       target == GL_TEXTURE_1D_ARRAY ||
+       target == GL_TEXTURE_2D_ARRAY) {
+      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
+                       "glGenerateMipmap() to %s target\n",
+                       _mesa_lookup_enum_by_nr(target));
+      return GL_TRUE;
+   }
+
+   srcLevel = texObj->BaseLevel;
+   baseImage = _mesa_select_tex_image(ctx, texObj, target, srcLevel);
+   if (!baseImage) {
+      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
+                       "glGenerateMipmap() couldn't find base teximage\n");
+      return GL_TRUE;
+   }
+
+   if (_mesa_is_format_compressed(baseImage->TexFormat)) {
+      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
+                       "glGenerateMipmap() with %s format\n",
+                       _mesa_get_format_name(baseImage->TexFormat));
+      return GL_TRUE;
+   }
+
+   if (_mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB &&
+       !ctx->Extensions.EXT_texture_sRGB_decode) {
+      /* The texture format is sRGB but we can't turn off sRGB->linear
+       * texture sample conversion.  So we won't be able to generate the
+       * right colors when rendering.  Need to use a fallback.
+       */
+      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
+                       "glGenerateMipmap() of sRGB texture without "
+                       "sRGB decode\n");
+      return GL_TRUE;
+   }
+
+   /*
+    * Test that we can actually render in the texture's format.
+    */
+   if (!mipmap->FBO)
+      _mesa_GenFramebuffers(1, &mipmap->FBO);
+   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, mipmap->FBO);
+
+   if (target == GL_TEXTURE_1D) {
+      _mesa_FramebufferTexture1D(GL_FRAMEBUFFER_EXT,
+                                    GL_COLOR_ATTACHMENT0_EXT,
+                                    target, texObj->Name, srcLevel);
+   }
+#if 0
+   /* other work is needed to enable 3D mipmap generation */
+   else if (target == GL_TEXTURE_3D) {
+      GLint zoffset = 0;
+      _mesa_FramebufferTexture3D(GL_FRAMEBUFFER_EXT,
+                                    GL_COLOR_ATTACHMENT0_EXT,
+                                    target, texObj->Name, srcLevel, zoffset);
+   }
+#endif
+   else {
+      /* 2D / cube */
+      _mesa_FramebufferTexture2D(GL_FRAMEBUFFER_EXT,
+                                    GL_COLOR_ATTACHMENT0_EXT,
+                                    target, texObj->Name, srcLevel);
+   }
+
+   status = _mesa_CheckFramebufferStatus(GL_FRAMEBUFFER_EXT);
+
+   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, fboSave);
+
+   if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+      _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
+                       "glGenerateMipmap() got incomplete FBO\n");
+      return GL_TRUE;
+   }
+
+   return GL_FALSE;
+}
+
+void
+_mesa_meta_glsl_generate_mipmap_cleanup(struct gen_mipmap_state *mipmap)
+{
+   if (mipmap->VAO == 0)
+      return;
+   _mesa_DeleteVertexArrays(1, &mipmap->VAO);
+   mipmap->VAO = 0;
+   _mesa_DeleteBuffers(1, &mipmap->VBO);
+   mipmap->VBO = 0;
+
+   _mesa_meta_blit_shader_table_cleanup(&mipmap->shaders);
+}
+
+/**
+ * Called via ctx->Driver.GenerateMipmap()
+ * Note: We don't yet support 3D textures, 1D/2D array textures or texture
+ * borders.
+ */
+void
+_mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
+                          struct gl_texture_object *texObj)
+{
+   struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
+   struct vertex verts[4];
+   const GLuint baseLevel = texObj->BaseLevel;
+   const GLuint maxLevel = texObj->MaxLevel;
+   const GLint maxLevelSave = texObj->MaxLevel;
+   const GLboolean genMipmapSave = texObj->GenerateMipmap;
+   const GLuint fboSave = ctx->DrawBuffer->Name;
+   const GLuint currentTexUnitSave = ctx->Texture.CurrentUnit;
+   const GLboolean use_glsl_version = ctx->Extensions.ARB_vertex_shader &&
+                                      ctx->Extensions.ARB_fragment_shader;
+   GLenum faceTarget;
+   GLuint dstLevel;
+   const GLint slice = 0;
+   GLuint samplerSave;
+
+   if (_mesa_meta_check_generate_mipmap_fallback(ctx, target, texObj)) {
+      _mesa_generate_mipmap(ctx, target, texObj);
+      return;
+   }
+
+   if (target >= GL_TEXTURE_CUBE_MAP_POSITIVE_X &&
+       target <= GL_TEXTURE_CUBE_MAP_NEGATIVE_Z) {
+      faceTarget = target;
+      target = GL_TEXTURE_CUBE_MAP;
+   } else {
+      faceTarget = target;
+   }
+
+   _mesa_meta_begin(ctx, MESA_META_ALL);
+
+   /* Choose between glsl version and fixed function version of
+    * GenerateMipmap function.
+    */
+   if (use_glsl_version) {
+      _mesa_meta_setup_vertex_objects(&mipmap->VAO, &mipmap->VBO, true,
+                                      2, 3, 0);
+      _mesa_meta_setup_blit_shader(ctx, target, &mipmap->shaders);
+   } else {
+      _mesa_meta_setup_ff_tnl_for_blit(&mipmap->VAO, &mipmap->VBO, 3);
+      _mesa_set_enable(ctx, target, GL_TRUE);
+   }
+
+   samplerSave = ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler ?
+      ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler->Name : 0;
+
+   if (currentTexUnitSave != 0)
+      _mesa_BindTexture(target, texObj->Name);
+
+   if (!mipmap->FBO) {
+      _mesa_GenFramebuffers(1, &mipmap->FBO);
+   }
+
+   if (!mipmap->Sampler) {
+      _mesa_GenSamplers(1, &mipmap->Sampler);
+      _mesa_BindSampler(ctx->Texture.CurrentUnit, mipmap->Sampler);
+
+      _mesa_SamplerParameteri(mipmap->Sampler,
+                              GL_TEXTURE_MIN_FILTER,
+                              GL_LINEAR_MIPMAP_LINEAR);
+      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+      _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+      /* We don't want to encode or decode sRGB values; treat them as linear.
+       * This is not technically correct for GLES3 but we don't get any API
+       * error at the moment.
+       */
+      if (ctx->Extensions.EXT_texture_sRGB_decode) {
+         _mesa_SamplerParameteri(mipmap->Sampler, GL_TEXTURE_SRGB_DECODE_EXT,
+               GL_SKIP_DECODE_EXT);
+      }
+   } else {
+      _mesa_BindSampler(ctx->Texture.CurrentUnit, mipmap->Sampler);
+   }
+
+   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, mipmap->FBO);
+
+   _mesa_TexParameteri(target, GL_GENERATE_MIPMAP, GL_FALSE);
+
+   /* Silence valgrind warnings about reading uninitialized stack. */
+   memset(verts, 0, sizeof(verts));
+
+   /* Setup texture coordinates */
+   _mesa_meta_setup_texture_coords(faceTarget,
+                                   slice,
+                                   0, 0, 1, /* width, height never used here */
+                                   verts[0].tex,
+                                   verts[1].tex,
+                                   verts[2].tex,
+                                   verts[3].tex);
+
+   /* setup vertex positions */
+   verts[0].x = -1.0F;
+   verts[0].y = -1.0F;
+   verts[1].x =  1.0F;
+   verts[1].y = -1.0F;
+   verts[2].x =  1.0F;
+   verts[2].y =  1.0F;
+   verts[3].x = -1.0F;
+   verts[3].y =  1.0F;
+
+   /* upload vertex data */
+   _mesa_BufferData(GL_ARRAY_BUFFER_ARB, sizeof(verts),
+                       verts, GL_DYNAMIC_DRAW_ARB);
+
+   /* texture is already locked, unlock now */
+   _mesa_unlock_texture(ctx, texObj);
+
+   for (dstLevel = baseLevel + 1; dstLevel <= maxLevel; dstLevel++) {
+      const struct gl_texture_image *srcImage;
+      const GLuint srcLevel = dstLevel - 1;
+      GLsizei srcWidth, srcHeight, srcDepth;
+      GLsizei dstWidth, dstHeight, dstDepth;
+      GLenum status;
+
+      srcImage = _mesa_select_tex_image(ctx, texObj, faceTarget, srcLevel);
+      assert(srcImage->Border == 0);
+
+      /* src size */
+      srcWidth = srcImage->Width;
+      srcHeight = srcImage->Height;
+      srcDepth = srcImage->Depth;
+
+      /* new dst size */
+      dstWidth = MAX2(1, srcWidth / 2);
+      dstHeight = MAX2(1, srcHeight / 2);
+      dstDepth = MAX2(1, srcDepth / 2);
+
+      if (dstWidth == srcImage->Width &&
+          dstHeight == srcImage->Height &&
+          dstDepth == srcImage->Depth) {
+         /* all done */
+         break;
+      }
+
+      /* Allocate storage for the destination mipmap image(s) */
+
+      /* Set MaxLevel large enough to hold the new level when we allocate it */
+      _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, dstLevel);
+
+      if (!_mesa_prepare_mipmap_level(ctx, texObj, dstLevel,
+                                      dstWidth, dstHeight, dstDepth,
+                                      srcImage->Border,
+                                      srcImage->InternalFormat,
+                                      srcImage->TexFormat)) {
+         /* All done.  We either ran out of memory or we would go beyond the
+          * last valid level of an immutable texture if we continued.
+          */
+         break;
+      }
+
+      /* limit minification to src level */
+      _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, srcLevel);
+
+      /* Set to draw into the current dstLevel */
+      if (target == GL_TEXTURE_1D) {
+         _mesa_FramebufferTexture1D(GL_FRAMEBUFFER_EXT,
+                                       GL_COLOR_ATTACHMENT0_EXT,
+                                       target,
+                                       texObj->Name,
+                                       dstLevel);
+      }
+      else if (target == GL_TEXTURE_3D) {
+         GLint zoffset = 0; /* XXX unfinished */
+         _mesa_FramebufferTexture3D(GL_FRAMEBUFFER_EXT,
+                                       GL_COLOR_ATTACHMENT0_EXT,
+                                       target,
+                                       texObj->Name,
+                                       dstLevel, zoffset);
+      } else {
+         /* 2D / cube */
+         _mesa_FramebufferTexture2D(GL_FRAMEBUFFER_EXT,
+                                       GL_COLOR_ATTACHMENT0_EXT,
+                                       faceTarget,
+                                       texObj->Name,
+                                       dstLevel);
+      }
+
+      _mesa_DrawBuffer(GL_COLOR_ATTACHMENT0_EXT);
+
+      /* sanity check */
+      status = _mesa_CheckFramebufferStatus(GL_FRAMEBUFFER_EXT);
+      if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+         _mesa_problem(ctx, "Unexpected incomplete framebuffer in "
+                       "_mesa_meta_GenerateMipmap()");
+         break;
+      }
+
+      assert(dstWidth == ctx->DrawBuffer->Width);
+      assert(dstHeight == ctx->DrawBuffer->Height);
+
+      /* setup viewport */
+      _mesa_set_viewport(ctx, 0, 0, 0, dstWidth, dstHeight);
+
+      _mesa_DrawArrays(GL_TRIANGLE_FAN, 0, 4);
+   }
+
+   _mesa_lock_texture(ctx, texObj); /* relock */
+
+   _mesa_BindSampler(ctx->Texture.CurrentUnit, samplerSave);
+
+   _mesa_meta_end(ctx);
+
+   _mesa_TexParameteri(target, GL_TEXTURE_MAX_LEVEL, maxLevelSave);
+   if (genMipmapSave)
+      _mesa_TexParameteri(target, GL_GENERATE_MIPMAP, genMipmapSave);
+
+   _mesa_BindFramebuffer(GL_FRAMEBUFFER_EXT, fboSave);
+}